Morphological parameters associated with middle cerebral artery aneurysms

Background: Morphological factors contribute to the hemodynamics of the middle cerebral artery (MCA). OBJECTIVE: To identify image-based morphological parameters that correlated with the presence of MCA aneurysms. METHODS: Image-based anatomic parameters obtained from 110 patients with and without MCA bifurcation aneurysms were evaluated with Slicer, an open-source image analysis software, to generate 3-dimensional models of the aneurysms and surrounding vascular architecture. We examined segment lengths, diameters, and vessel-to-vessel angles of the parent and daughter vessels at the MCA bifurcation. In order to reduce confounding by genetic and clinical risk factors, 2 control groups were selected: group A (the unaffected contralateral side of patients with unilateral MCA bifurcation aneurysms) and group B (patients without intracranial aneurysms or other vascular malformations). Univariate and multivariate analyses were performed to determine statistical significance. RESULTS: One hundred ten patients who were evaluated from 2007 to 2014 were analyzed (73 patients with MCA aneurysms and 37 control patients). Multivariate analysis revealed that a smaller parent artery diameter (group A: odds ratio [OR] 0.20, P <.01, group B: OR 0.23, P <.01) and a larger daughter-to-daughter branch angle (group A: OR 1.01, P.04, group B: OR 1.02, P.04) were most strongly associated with MCA aneurysm presence after adjusting for other morphological factors. CONCLUSION: Smaller parent artery diameter and larger daughter-to-daughter branch angles are associated with the presence of MCA bifurcation aneurysms. These easily measurable parameters may provide objective metrics to assess aneurysm formation and growth risk stratification in high-risk patients. ABBREVIATIONS: CI, confidence interval CTA, computed tomography angiography ICA, internal carotid artery IA, intracranial aneurysm MCA, middle cerebral artery PCoA, posterior communication artery WSS, wall shear stress.